1. The Field of the Invention
The field of the invention pertains to powered top coverings for open-top semi-trailer truck bodies and means for operating them.
2. Description of the Prior Art
The prior art discloses a variety of devices for enclosing open-top semi-trailers of the transfer type. It must be understood, by way of introduction, that debris carrying open-top semi-trailers, or those carrying loose commodities, are now subject to federal, state, and municipal statutes, laws or regulations which prohibit their uncovered use in transport on roads and highways, in order to prevent debris or loose contents from flying out onto the roads, thereby creating hazards to traffic and polluting the environment with such debris. Almost universally coverings are mandated by law or regulation to prevent this.
Early efforts disclose the use of tarpaulin coverings which are stretched over the trailer body top opening and tied down to posts or eyes provided on the walls of the body. This is time-consuming and inconvenient for the loader and provides limited access to the semi-trailer through the top, a circumstance which is frequently confronted. Stretching coverings across half-frames which are sectionally installed on hinges and optionally joined to each other along the trailer top are also known. These are manually swung open or closed by poles or crooks which are carried on the sides of the trailer or undercarriage. The disadvantages of this type of cover are that the poles become lost; the person loading is put to substantial inconvenience fitting the pole to a section-end to swing it open or closed (often having to climb over parts of the trailer or tractor to gain access to the section where it is attached), with the problem of manual tie-down remaining, albeit confined to fewer points for tying. The frames, by their elongated nature, are subject to misalignment and distortion because the swing is uncontrolled and depends on gravity.
Opening or closing the cover frames by manually operated, chain driven gear mechanisms which drive the hinged ends of the frames to get the opening/closing swing are also known in the art. See Exhibit "A" in the patented file showing a product of such design of Anji Manufacturing, Inc. The disadvantages of such means are the physical effort required of the loader, the inherent physical danger and discomfort of using a chain by hand and the stowage in a safe place of the chain so that it does not become free and capable of doing damage. A further disadvantage is that the gear mechanism directly drives the member of the frame about which the cover rotates. The mechanism applies severe torque to the frame, is cumbersome and is located inconveniently on the trailer body. Also, the free, or inboard end, of the frame is unsupported and the frame is subject to substantial distortion when moved. Power means applied to chain-driven closures are also known. These obviously reduce physical fatigue and eliminate some hazard, but the disadvantages of no support to the free end of the frame, a cumbersome, unsafe arrangement, and severe torque at the wrong place remain. Additionally, the frames are difficult to stop in mid-cycle with any precision which is also a disadvantage in loading or removal. Another type of powered apparatus for opening and closing frames is known wherein the inboard cabside corner of the frame is provided with an outwardly mounted stop which is struck and contacted by a free end of an arm rotated by a motor and the swing motion imparted to the frame thereby allows it to rise under power and fall by gravity to the open or closed position. The impact of free-fall causes severe distortion to the frame and there is no option provided to permit partial opening or closure. Although no literature is available to Applicants, upon information and belief, Ace Manufacturing Company of California produces such an apparatus.
The present invention eliminates all of the disadvantages recited above by providing powered rotating arms and rollers in continuous assembly and contact with tracks which form inboard transverse edges of the frames, permitting precise, positive opening and closing with interim semi-open positions possible, support for the frames at all times, and also provides complete operator safety and convenience, with novel, built-in means to allow for compensation of misalignment of the frames to ensure complete closure.
Other numerous advantages over the prior art and novel and unique features of the present invention are described in detail below.